There are wide variety of office chairs that have been designed to be more ergonomic and provide a variety of different functions and adjustments. These adjustments generally include height and back support and more specifically lumbar support for the spine and the back in general that are susceptible to the harmful effects of a prolonged sitting position. In general lumbar supports have included adjustments to the height of the lumbar support relative the chair back so that the spinal support can be adjusted relative to the height of the individual. Other adjustment mechanisms have focused on adjusting the depth of spinal support that the lumbar support can provide.
Prior art lumbar supports have been devised to address the noted problems. For example, U.S. Pat. No. 6,572,190 issued on Jun. 3, 2003 to Koepke e al. This patent relates to a lumbar support for a chair having a flexible back, includes at least one generally vertical support member disposed to the rear of the chair back. A transverse member engages the vertical support and has opposed ends provided with grippers for gripping opposed edges of the flexible back. The transverse member is configured to force the opposed edges of the flexible back forwardly of the chair back in the lumbar region of the user to provide support.
De Pascal et al. is the owner of U.S. Pat. No. 5,718,476 which issued on Feb. 17, 1998. This patent relates to an office chair has a seat supported by a base. A seat back is resiliently attached to the seat. A pair of axles support upper cams and lower cams, respectively. A stiff, flexible sheet is attached to the seat back and extends over and is supported by the upper and lower cams. As a mechanical linkage which interconnects the cams with each other and an operator controlled knob coordinately rotates the cams, the curvature of the flexible sheet continuously changes its contour. More specifically, the contour flows such that a salient point (S) of maximum contact with the lumbar region of the user shifts in a vertical direction (h) and in a horizontal direction (e) simultaneously and concurrently.
Raftery et al. is the owner of U.S. Pat. No. 6,848,744 which issued on Feb. 1, 2005. This patent relates to a chair back comprises a back frame, a movable back support, and a contouring assembly. The back frame includes a portion rearward of the back support. The contouring assembly is coupled to the back support and the portion of the back frame. The contouring assembly pulls the back support toward the portion of the back frame. The present invention is also directed to a chair including such a chair back.
Deimen et al. is the owner of U.S. Pat. No. 6,811,218 which issued on Nov. 2, 2004. This patent relates to a task chair including a seat support structure, and a seat supported by the seat support structure and having a seating surface which may ergonomically conform to a seated user. The seating surface includes rigid and flexible portions connected to one another, the flexible portions allowing resilient flexing of the seating surface to create conformance zones which dynamically support a seated user in an ergonomic manner.
Thus an adjustable lumbar support for a chair back which is easy for the individual to adjust, includes flexing zones that maintains the ergonomics of the chair back, provides improved spinal support, allows for lumbar support along a horizontal plane therefore adjusting the entire chair back, and is not visible through the chair back is desirable.